<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%@taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <base href="<%=basePath%>">
    
    <title>My JSP 'ajax2.jsp' starting page</title>
    
	<meta http-equiv="pragma" content="no-cache">
	<meta http-equiv="cache-control" content="no-cache">
	<meta http-equiv="expires" content="0">    
	<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
	<meta http-equiv="description" content="This is my page">
	<!--
	<link rel="stylesheet" type="text/css" href="styles.css">
	-->
	<script type="text/javascript">
	function createXMLHttpRequest(){
		try {
			return new XMLHttpRequest();
		} catch (e) {
			try {
				return ActvieXObject("Msxml2.XMLHTTP");//IE6.0
			} catch (e) {
				try {
					return ActvieXObject("Microsoft.XMLHTTP");
				} catch (e) {
					alter("浏览器不兼容");
					throw e;
				}
			}
		}
	}
	window.onload=function(){
		var userEle=document.getElementById("usernameEle")
		userEle.onblur=function(){
			var xmlHttp=createXMLHttpRequest();
			xmlHttp.open("POST","<c:url value='/ValidataUsernameServlet'/>",true);
			xmlHttp.setRequestHeader("Content-Type","application/x-www-form-urlencoded");
			xmlHttp.send("username="+userEle.value);
			xmlHttp.onreadystatechange=function(){
				if(xmlHttp.readyState==4&&xmlHttp.status==200){
					var text=xmlHttp.responseText;
					var span=document.getElementById("err")
					if(text=="1"){
						span.innerHTML="用户名已被注册";
						
					}else{
						span.innerHTML="";
					}
				}
				
				
			}
		}
		
		
	}
	
	
	</script>

  </head>
  
  <body>
    This is my JSP page. <br>
    <form action="" method="post">
    用户名<input type="text" name="username" id="usernameEle"><span id="err"></span><br>
    密 码<input type="password"><br>
<input type="submit" id="btn" value="注册">
    </form>
    
    
  </body>
</html>
